Method for employing single fault safe redundant signals

ABSTRACT

An electrosurgical system includes an electrosurgical instrument coupled to an electrosurgical generator. The electrosurgical system may include a first sensor and a second sensor, which are configured to detect redundant tissue properties and output a signal corresponding thereto. The electrosurgical system has a signal processing circuit for receiving and modifying the output signal from the second sensor. The electrosurgical generator may include a controller for receiving an output signal from the first sensor and a processed signal from the signal processing circuit. The controller compares the two signals received and shuts down the system based on the comparison of the first sensor and a processed signal.

BACKGROUND

1. Technical Field

The present disclosure is directed to electrosurgery. More particularly, the present disclosure is directed to an electrosurgical system and method for detecting single fault conditions in sensor assemblies.

2. Background of the Related Art

Devices containing electrical systems require various performance measures to ensure safety. Such safety requirements are particularly important in the case of medical equipment which comes into contact with a patient. Generally, one or more sensors collect data representing the operating condition of the system. After the sensors collect such data, a controller compares the collected data to predetermined threshold values in order to determine whether the system is operating in an unsafe condition.

Accordingly, there is a need for a system and method to mitigate the risk associated with single fault conditions in electrosurgical systems.

SUMMARY

As used herein, the phrases “in an embodiment,” “in embodiments,” “in some embodiments,” or “in other embodiments,” which may each refer to one or more of the same or different embodiments in accordance with the present disclosure. As used herein, a phrase in the form “A/B” means A or B. As used herein, a phrase in the form “A and/or B” means “(A), (B), or (A and B)”. For the purposes of this description, a phrase in the form “at least one of A, B, or C” means “(A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C)”.

As used herein, the term “RF” generally refers to electromagnetic waves having a lower frequency than microwaves. Electromagnetic energy is generally classified by increasing energy or decreasing wavelength into radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma-rays. As used herein, the term “microwave” generally refers to electromagnetic waves in the frequency range of 300 megahertz (MHz) (3×10⁸ cycles/second) to 300 gigahertz (GHz) (3×10¹¹ cycles/second). As used herein, the term “ultrasound” generally refers to cyclic sound pressure with a frequency greater than the upper limit of human hearing.

As used herein, the term “sensor” generally refers to any sensing device capable of generating a signal representative of a value. As used herein, the term “processor” and “signal processing circuit” generally refers to an electronic circuit including analog and/or digital logic components capable of executing a set of instructions.

According to at least one aspect of the disclosure herein, an electrosurgical system includes a first sensor configured to output a first signal indicative of tissue property, a second sensor configured to output a second signal indicative of the tissue property, a signal processing circuit operatively coupled to the second sensor for receiving the second signal and outputting a processed signal, and a controller for receiving the first signal the first sensor and the processed signal from the signal processing circuit, wherein the controller compares the first signal to the processed signal.

According to yet another aspect of the disclosure herein, the signal processing circuit delays the second signal for a predetermined time period to generate the processed signal.

According to another aspect of the disclosure herein, the signal processing circuit inverts the second signal from an original waveform to the processed signal and outputs the processed signal.

According to yet another aspect of the disclosure herein, the controller turns off the system when the first signal and processed signal are identical.

According to another aspect of the disclosure herein, the controller converts the processed signal to the original waveform when the first signal and the processed signal are unique.

According to still another aspect of the disclosure herein, a method for employing single fault safe redundant signals for an electrosurgical system is disclosed and includes the step of providing a source of electrosurgical energy to treat tissue. The method further includes the steps of detecting an energy property using a first sensor and a second sensor; outputting a first voltage signal from the first sensor and a second voltage signal for the second sensor; processing the second voltage signal; and comparing the first voltage signal to the processed second voltage signal through the controller.

The method may further include the step of delaying the second voltage signal for a predetermined time period, on the step of inverting the second voltage signal from an original waveform to the processed second voltage signal.

The method may include the step of shutting down the system when the first voltage signal and processed second voltage signal are identical, or may further include the step of converting the second processed signal to the original waveform when the first voltage signal and processed second voltage signal are unique.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the present disclosure will become more apparent in light of the following detailed description when taken in conjunction with the accompanying drawings in which:

FIGS. 1A-1B are schematic block diagrams of electrosurgical systems in accordance with an embodiment of the present disclosure;

FIG. 2 is a block diagram view of an electrosurgical generator according to an embodiment of the present disclosure;

FIG. 3 is a perspective view of a processor according to the present disclosure; and

FIGS. 4A and 4B are tables illustrating a grid array of the processor of FIG. 3 according to the present disclosure.

DETAILED DESCRIPTION

Particular embodiments of the present disclosure are described hereinbelow with reference to the accompanying drawings; however, it is to be understood that the disclosed embodiments are examples of the disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. Like reference numerals may refer to similar or identical elements throughout the description of the figures.

The generator according to the present disclosure can perform ablation, monopolar and bipolar electrosurgical procedures, including vessel sealing procedures. The generator may include a plurality of outputs for interfacing with various electrosurgical instruments (e.g., a monopolar active electrode, return electrode, bipolar electrosurgical forceps, footswitch, ablation needle, ultrasonic transducers, etc.). Further, the generator includes electronic circuitry configured for generating microwave, radio frequency and/or acoustic energy specifically suited for various electrosurgical modes (e.g., cutting, blending, division, etc.) and procedures (e.g., ablation, monopolar, bipolar, vessel sealing).

FIG. 1A is a schematic illustration of a monopolar electrosurgical system 100 according to one embodiment of the present disclosure. The system 100 includes an electrosurgical instrument 102 having one or more electrodes for treating tissue of a patient P. The instrument 102 is a monopolar type instrument including one or more active electrodes (e.g., electrosurgical cutting probe, ablation electrode(s), etc.). Energy is supplied to the instrument 102 by a generator 200 via a supply line 104, which is connected to an active terminal (not explicitly shown) of the generator 200, allowing the instrument 102 to coagulate, ablate and/or otherwise treat tissue. The energy is returned to the generator 200 through a return electrode 106 via a return line 108 at a return terminal (not explicitly shown) of the generator 200. The active terminal and the return terminal are connectors configured to interface with plugs (not explicitly shown) of the instrument 102 and the return electrode 106, which are disposed at the ends of the supply line 104 and the return line 108, respectively.

The system 100 may include a plurality of return electrodes 106 that are arranged to minimize the chances of tissue damage by maximizing the overall contact area with the patient P. In addition, the generator 200 and the return electrode 106 may be configured for monitoring so-called “tissue-to-patient” contact to insure that sufficient contact exists therebetween to further minimize chances of tissue damage. In one embodiment, the active electrode 6 may be used to operate in a liquid environment, wherein the tissue is submerged in an electrolyte solution.

FIG. 1B is a schematic illustration of a bipolar electrosurgical system 103 according to the present disclosure. The system 103 includes a bipolar electrosurgical forceps 110 having one or more electrodes for treating tissue of a patient P. The electrosurgical forceps 110 include opposing jaw members having an active electrode 114 and a return electrode 116, respectively, disposed therein. The active electrode 114 and the return electrode 116 are connected to the generator 200 through cable 118, which includes the supply and return lines 104, 108 coupled to the active and return terminals. The electrosurgical forceps 110 are coupled to the generator 200 at a connector 121 having connections to the active and return terminals (e.g., pins) via a plug disposed at the end of the cable 118, wherein the plug includes contacts from the supply and return lines 104, 108. In other embodiments, generator 200 may be integrated into the forceps 110.

Referring to FIG. 2, the generator 200 includes a controller 202 for monitoring and controlling the generator 200, a power supply 204 (“HVPS”), which may be a high voltage DC power supply, and an output stage 206. The HVPS 204 is connected to an AC source (e.g., electrical wall outlet) and provides high voltage DC power to an output stage 206, which then converts high voltage DC power into treatment energy (e.g., laser, ultrasonic, electrosurgical or microwave) and delivers the energy to the active terminal 4. The energy is returned thereto via the return terminal 8. The output stage 206 is configured to operate in a plurality of modes, during which the generator 200 outputs corresponding waveforms having specific duty cycles, peak voltages, crest factors, etc. In another embodiment, the generator 200 may be based on other types of suitable power supply topologies.

The controller 202 includes a processor 208 operably connected to a memory 210. The memory 210 may include non-transitory storage (e.g., flash media, disk media, etc.) and/or transitory (e.g., random-access memory) medium readable by a computer (e.g., controller 202) and includes, but is not limited to non-volatile type memory. The processor 208 includes one or more output ports that are connected to the HVPS 204 and/or output stage 206 allowing the processor 208 to control the output of the generator 200 according to either open and/or closed control loop schemes. Those skilled in the art will appreciate that the processor 208 may be substituted by any logic processor (e.g., control circuit) adapted to perform the calculations discussed herein. In embodiments, the processor 208 may be an integrated circuit as shown in FIG. 3, which is described in further detail below.

The generator 200 includes a plurality of sensors, namely, a first sensor 220 a and a second sensor 220 b that provide feedback to the controller 202. The sensors 220 a and 220 b measure tissue and/or energy property while the generator 200 is in use. Suitable tissue properties include temperature, real and/or imaginary impedance, conductivity, transmittance, opacity, and the like. Suitable energy properties include voltage, current, power, energy, phase, and the like. Non-limiting examples of sensors 220 a and 220 b suitable for measuring tissue and/or energy properties may include thermal sensors, electromagnetic field sensors, impedance monitors, optical sensors, transformers, capacitive sensors, and any combinations thereof.

In embodiments, the first sensor 220 a and the second sensor 220 b are configured to measure an identical tissue or energy property thereby providing redundant sensor signals to the controller 202. The sensors 220 a and 220 b output sensor signals indicative of the measured tissue or energy property as an analog electrical signal or a digital signal. The signal output by each of the sensors 220 a and 220 b are used to determine if generator 200 is functioning properly by comparing the two signals to detect a fault. The sensors 220 a and 220 b may be of substantially identical design and construction and produce substantially equivalent output signals.

The controller 202 determines a fault in the operation of the generator 200 by comparing redundant sensor signals from two or more sensors (e.g., sensors 220 a and 200 b) measuring an identical tissue and/or energy property. As part of a safety check, the controller 202 compares redundant output signals. If the controller 202 determines that the signals from the sensors 220 a and 220 b are substantially different, namely, the difference between the signals is greater than a predetermined threshold, then it is determined that a fault in the generator has occurred. However, this setup alone is unable to determine a single fault condition which may be caused by a physical short between the outputs of the sensors 220 a and 220 b and/or inputs from the sensors 220 a and 220 b at the controller 202, namely, the processor 208. In particular, the short results in the same signals being provided to the controller 202, which may lead to the controller 202 to incorrectly determine that the generator 200 is operating properly. In other words, regardless of a discrepancy in actual sensor readings, the controller 200 continues to receive substantially identical signals, namely, the difference between the signals is less than a predetermined threshold. As a result, the controller 202 determines incorrectly that there is no fault in the operation of the generator 200. This may result in an unsafe condition that is unacceptable for an electrosurgical system.

As described above, the first and second sensors 220 a and 220 b measures an identical tissue and/or energy property and output first and second signals, respectively. Electrosurgical generator 200 includes a signal processing circuit 224 operatively coupled to second sensor 220 b. Signal processing circuit 224 is configured to modify the output received from second sensor 220 b, thus converting the second signal to a processed signal. Signal processing circuit 224 may include any analog or digital components that can be used to convert the second sensor signal into the processed signal. Signal processing circuit 224 may modify the signal of the second sensor 220 b by delaying, gain scaling, or phase inverting the signal before being received by controller 202. The signal processing circuit 224 may include any suitable circuit components such as operational amplifiers, integrators, and the like, to modify the signals.

Controller 202 receives the first signal from first sensor 220 a and the processed signal from signal processing circuit 224. Controller 202 compares the two signals received to determine if a single fault condition exists. If the first signal and processed signal are different by a predetermined amount, the controller 202 establishes that no single fault exists and processed signal is converted into the original second signal. Thereafter, the controller 202 compares the first signal and the original second signal to determine if an output fault exists. If an output fault exists, then the controller 202 may either issue an alarm or terminate output of the generator 202. However, if the first signal and processed signal are identical, the controller 202 detects a single fault. In embodiments, the controller 202 may similarly issue an alarm and/or signal the generator 200 to shut down to prevent damage to the patient upon encountering single fault and/or output fault in the generator 200.

A single fault condition may occur as a result of a physical short developing within the hardware of generator 200. As described above, the controller 202 and/or the processor 208 may be an integrated circuit, or a chip 300 as shown in FIG. 3. The chip 300 includes a microelectronic device (e.g., processor 208) mounted on one side of a substrate. On the opposite side of the substrate is an array of contacts, which includes a plurality of connectors arranged in a two-dimensional grid array 302. Each contact provides the electrical connection between the chip 300 and a circuit board. In embodiments, the array 302 may be a ball grid array having a plurality of contact surfaces or a pin grid array having a plurality of pins configured to interface with corresponding connectors disposed on the circuit board. In further embodiments, the array 302 may be any other suitable surface-mount packaging used for integrated circuits.

The array 302 includes a plurality of columns, namely, columns 1, 2, 3, 4, and a plurality of rows, namely, rows, a, b, c, d. The present disclosure provides for a contact grid array configuration that minimizes incidence of single fault conditions. FIG. 4A shows a table of sensor signals provided to the chip 300. In this configuration, redundant sensor signals are being fed to adjacent pins, e.g., connectors a1 and a2, a3 and a4, b1 and b2, etc. In this configuration, adjacent pins receive signals from redundant components. However, there is a possibility that a short may be caused when these signals from redundant components are directed at adjacent pins.

As shown in FIG. 4B, the sensor signals provided to the chip 300 are rerouted such that redundant signals are positioned at non-adjacent pins. More specifically, the signal from the first sensor detecting voltage, RF_V_1, is positioned at pin a1. The redundant signal from second sensor, RF_V_2, is positioned at c1, thereby preventing a short occurring from two redundant signals at adjacent pins. Further, the first sensor detecting temperature at tissue site, TEMP_1, is positioned at a2 whereas the second sensor, TEMP_2, is positioned at c2. This configuration of controller 202 poses the greatest challenge for a short to occur as redundant pins are surrounded by pins receiving distinct signals on all sides. In this configuration, none of the redundant signals are provided to connectors disposed adjacent to each other. In other words, each of the connectors provided redundant signals corresponding to a first tissue and/or energy property is separated from its counterpart connector by one or more connectors receiving a signal corresponding to another tissue and/or energy property.

Further disclosed is a method for employing single fault redundant signals. The method has the step of detecting one or more redundant tissue properties using at least two sensors disposed on an electrosurgical instrument as described above. Each sensor provides a signal indicative of a tissue property or ambient property.

The method further includes the step of processing at least one sensor signal through a signal processing circuit by delaying for a predetermined time period, gain scaling, or phase inverting the signal to form a processed signal. Controller next compares the at least one sensor signal to the processed signal to determine if a single fault exists in the system.

The method may further include the step of shutting down the system when two signals are identical. The method may further include the step of converting the processed signal to the original sensor signal when the signals are unique. The method may further include comparing the original sensor signal to a redundant signal from a redundant sensor configured to measure the identical tissue and/or energy property and shutting down the system when the redundant sensor signals are substantially different.

It should be understood that the foregoing description is only illustrative of the present disclosure. Various alternatives and modifications can be devised by those skilled in the art without departing from the disclosure. Accordingly, the present disclosure is intended to embrace all such alternatives, modifications, and variances. The embodiments described with reference to the attached drawing figs. are presented only to demonstrate certain examples of the disclosure. Other elements, steps, methods, and techniques that are insubstantially different from those described above and/or in the appended claims are also intended to be within the scope of the disclosure. 

What is claimed is:
 1. An electrosurgical generator comprising: a first sensor configured to output a first signal indicative of a tissue property; a second sensor configured to output a second signal indicative of the tissue property; a signal processing circuit operatively coupled to the second sensor, the signal processing circuit configured to receive the second signal, to modify the second signal into a processed signal, and to output the processed signal; and a controller configured to: receive the first signal from the first sensor, the second signal from the second sensor, and the processed signal from the signal processing circuit, compare the first signal to the processed signal, convert the processed signal back into the second signal based on a comparison of the first signal and the processed signal being different by a predetermined amount, and compare the first signal to the converted second signal.
 2. The electrosurgical generator according to claim 1, wherein the signal processing circuit is further configured to delay the second signal for a predetermined time period to generate the processed signal.
 3. The electrosurgical generator according to claim 1, wherein the signal processing circuit is further configured to invert the second signal to generate the processed signal.
 4. The electrosurgical generator according to claim 3, wherein the controller is configured to terminate output of the electrosurgical generator in response to the first signal and the processed signal being substantially identical.
 5. The electrosurgical generator according to claim 4, wherein the controller is further configured to convert the processed signal back into the second signal when the first signal and the processed signal are substantially different. 